The influence of the sulphonic group on the biodegradability of n-alkylbenzene sulphonates.

1. Model compounds of the type p-n-alkylbenzene sulphonates, p-n-alkylbenzoic acids and phenylcarboxylic acids were tested for biodegradability. Bioassays were performed with unadapted mixed cultures (soil suspensions) using the Organization for Economic Cooperation and Development (OECD) screening test. 2. Degradation was measured by dissolved organic carbon analysis and g.l.c. or h.p.l.c. 3. p-n-Alkylbenzene sulphonates were resistant to microbial attack. The carboxylated compounds with analogous structures, however, with one exception, were easily decomposed. 4. The results indicate that the persistent character of p-n-alkylbenzene sulphonates is mainly due to the sulphonic substituent.